Neonatal jaundice: unconjugated hyperbilirubinaemia

Overview & Definition

Neonatal jaundice, characterised by a yellow discolouration of the skin and sclerae from elevated bilirubin, is the single most common clinical problem in the newborn period, visible in approximately 60 per cent of term and 80 per cent of preterm infants. Unconjugated hyperbilirubinaemia accounts for the overwhelming majority of cases, arising from an imbalance between bilirubin production and hepatic clearance of this lipid-soluble heme degradation product. While most jaundice is benign and self-limiting, the potential for unconjugated bilirubin to cross the blood-brain barrier and cause irreversible neurological damage makes systematic assessment and risk stratification essential in every newborn. [3]

The clinical task is not merely to detect jaundice but to distinguish the common, benign physiological pattern from the minority of infants whose bilirubin will rise to dangerous levels. The key conceptual framework is that bilirubin toxicity is a function of both the total serum bilirubin concentration and the infant's vulnerability, which is amplified by prematurity, illness, haemolysis, hypoalbuminaemia, and acidosis. The goal of management is to prevent bilirubin from reaching levels at which acute bilirubin encephalopathy and its chronic sequela, kernicterus, can occur. [4]

The 2022 American Academy of Pediatrics guideline revision superseded the 2004 guideline with updated, gestational-age-specific phototherapy and exchange transfusion thresholds, revised risk factor definitions, and an increased emphasis on universal predischarge bilirubin screening with structured follow-up. Despite these advances, kernicterus remains a persistent, largely preventable cause of devastating neurological disability, and cases continue to occur due to failures in recognition, escalation, and follow-up. [2]

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1. [1]Bhutani VK Predictive ability of a predischarge hour-specific serum bilirubin for subsequent significant hyperbilirubinemia in healthy term and near-term newborns. Pediatrics, 1999.PMID 9917432
2. [2]Kemper AR Clinical Practice Guideline Revision: Management of Hyperbilirubinemia in the Newborn Infant 35 or More Weeks of Gestation. Pediatrics, 2022.PMID 35927462
3. [3]American Academy of Pediatrics Subcommittee on Hyperbilirubinemia Management of hyperbilirubinemia in the newborn infant 35 or more weeks of gestation. Pediatrics, 2004.PMID 15231951
4. [4]Watchko JF Bilirubin-induced neurologic damage--mechanisms and management approaches. N Engl J Med, 2013.PMID 24256380
5. [5]Watchko JF Bilirubin-Induced Neurotoxicity in the Preterm Neonate. Clin Perinatol, 2016.PMID 27235209
6. [6]Maisels MJ An approach to the management of hyperbilirubinemia in the preterm infant less than 35 weeks of gestation. J Perinatol, 2012.PMID 22678141
7. [7]Maisels MJ The natural history of jaundice in predominantly breastfed infants. Pediatrics, 2014.PMID 25049352
8. [8]Newman TB Numbers needed to treat with phototherapy according to American Academy of Pediatrics guidelines. Pediatrics, 2009.PMID 19403502
9. [9]Kaplan M Glucose-6-phosphate dehydrogenase deficiency and severe neonatal hyperbilirubinemia: a complexity of interactions between genes and environment. Semin Fetal Neonatal Med, 2010.PMID 19942489